Image display apparatus and head-mounted display

ABSTRACT

An image display apparatus includes laser light sources, a light combining section that combines laser light from the laser light sources, and an optical scanner that deflects drawing laser light from the light combining section for two-dimensional scanning. The optical axes of the laser light outputted from the laser light sources and directed toward the optical scanner are present in the same plane. Further, the optical scanner has a light reflection surface configured to be perpendicular to the plane when the optical scanner is not driven. The optical scanner deflects the drawing laser light reflected off the light reflection surface for two-dimensional scanning by causing the light reflection surface to swing within the plane and in the direction perpendicular to the plane.

BACKGROUND

1. Technical Field

The present invention relates to an image display apparatus and ahead-mounted display.

2. Related Art

One known image display apparatus for displaying an image on a screenincludes a light source and an optical scanner that deflects light fromthe light source for two-dimensional scanning (see JP-A-2011-154344, forexample).

The image display apparatus described in JP-A-2011-154344 includes threesemiconductor lasers, a beam supplying section including a coupling lenscorresponding to each of the semiconductor lasers, dichroic mirrors, anda collector lens, and a beam deflecting section that deflects a beamoutputted from the beam supplying section for two-dimensional scanning.A light reflection surface of a reflection mirror provided in the beamdeflecting section is parallel to the optical axis of the beam emittedfrom each of the semiconductor lasers and disposed in a position shiftedfrom the optical axis in the thickness direction of an enclosure. A flatmirror is therefore provided between the beam supplying section and thebeam deflecting section, and the beam outputted from the beam supplyingsection is reflected off the flat mirror in the thickness direction ofthe enclosure and is then incident on the reflection mirror of the beamdeflecting section.

In the image display apparatus described in JP-A-2011-154344, thethickness (size) of the enclosure can be reduced because the reflectionsurface of the reflection mirror is perpendicular to the thicknessdirection of the enclosure, but the number of parts increases because anextra member, such as the flat mirror for reflecting the beam in thethickness direction, is required. Unfortunately, this disadvantageouslyresults in an increase in the number of steps required to assemble theapparatus.

SUMMARY

An object of some aspects of the invention is to provide an imagedisplay apparatus that allows reduction not only in the number of partsbut also in the size of the apparatus and a head-mounted displayincluding the image display apparatus.

An image display apparatus according to an aspect of the inventionincludes a plurality of light source sections each of which outputs alight, a light combining section that combines the light from theplurality of light source sections, and an optical scan section thatdeflects the combined light from the light combining section fortwo-dimensional scanning around a first axis and a second axisperpendicular to the first axis, the optical axis of the light outputtedfrom each of the plurality of light source sections and directed throughthe light combining section toward the optical scan section is presentin a first plane, the optical scan section includes a base that swingsaround the first axis and the second axis, a light reflection platehaving a light reflection surface that reflects the light from the lightcombining section, the light reflection surface having an area largerthan the area of the base, and a spacer that connects the base and thelight reflection plate to each other, the first axis is present in thefirst plane, the second axis is parallel to a normal to the first plane,and the light reflection surface is configured to be perpendicular tothe first plane when the optical scan section is not driven.

The configuration described above allows the combined light from thelight combining section to be incident on the optical scan sectionwithout reflecting the combined light in a direction that intersects thefirst plane and hence eliminates the necessity for a flat mirror.Further, in the optical scan section, the mechanism for causing thelight reflection surface to swing can be smaller than the area of thelight reflection surface, whereby the area of the optical scan sectionalong the direction parallel to the light reflection surface can bereduced. The light reflection surface configured to be perpendicular tothe first plane therefore does not increase the size of the imagedisplay apparatus in the direction perpendicular to the first plane.That is, an image display apparatus that allows reduction not only inthe number of parts but also in size of the apparatus can be provided.

In the image display apparatus according to the aspect of the invention,it is preferable that the light reflection surface is irradiated withthe combined light traveling in a direction inclined to a normal to thelight reflection surface.

The light deflected by the optical scan section for two-dimensionalscanning is therefore incident on an object without interfering withother members in the apparatus. In other words, it is not necessary toprovide a flat mirror or any other optical component for changing theoptical path of the light deflected by the optical scan section fortwo-dimensional scanning, whereby the size of the image displayapparatus can be reduced.

In the image display apparatus according to the aspect of the invention,it is preferable that the amplitude of the swing motion of the basearound the first axis is greater than the amplitude of the swing motionof the base around the second axis.

In this way, an effective drawing region that is contained in a lightdrawable region and can be used to actually display an image can beincreased.

In the image display apparatus according to the aspect of the invention,it is preferable that the optical scan section includes a frame thatsurrounds the base, a support that supports the frame, a first shaftthat connects the base to the frame in such a way that the base isrotatable around the first axis relative to the frame, and a secondshaft that connects the frame to the support in such a way that theframe is rotatable around the second axis relative to the support.

The optical scan section described above has a simple configuration, andthe size of the optical scan section can be reduced.

In the image display apparatus according to the aspect of the invention,it is preferable that the light reflection plate is set apart (spacedapart) from the first shaft in a thickness direction of the lightreflection plate but overlaps with at least part of the first shaft whenviewed in the thickness direction.

Since the light reflection plate is set apart from the first shaft inthe thickness direction but overlaps with at least part of the firstshaft when viewed in the thickness direction, the size of the opticalscan section can be reduced.

In the image display apparatus according to the aspect of the invention,it is preferable that the first shaft is disposed in parallel to anin-plane direction in the first plane, and that the base is allowed toresonantly swing around the first axis by resonantly driving a firstoscillation system including the light reflection plate, the spacer, thebase, and the first shaft.

The base can therefore be allowed to swing around the first axis at alarge amplitude with a small amount of energy.

In the image display apparatus according to the aspect of the invention,it is preferable that the width of the frame in the direction of thenormal to the first plane is smaller than the width of the frame in thein-plane direction in the first plane.

The thickness of the image display apparatus can therefore be reduced.

In the image display apparatus according to the aspect of the invention,it is preferable that the optical scan section further includes apermanent magnet provided on the frame and a coil that faces the frameand produces a magnetic field that acts on the permanent magnet.

The width of the optical scan section in the in-plane direction of thelight reflection surface can therefore be reduced. The thus shapedoptical scan section is suitable for the image display apparatusaccording to the aspect of the invention.

It is preferable that the image display apparatus according to theaspect of the invention further includes a prism that is provided on theoptical axis of the combined light from the light combining section,inclines the optical axis of the combined light from the light combiningsection, and changes the cross-sectional shape of the combined light.

Shaping the cross-sectional shape of the combined light improves imagedisplay characteristics.

In the image display apparatus according to the aspect of the invention,it is preferable that the light from each of the light source sectionsis linearly polarized light that behaves as s-polarized light withrespect to a light incident surface of the prism.

In this way, for example, loss of the light produced when the lightpasses through the prism can be reduced.

In the image display apparatus according to the aspect of the invention,it is preferable that the prism increases the width of thecross-sectional shape of the combined light in the in-plane direction inthe first plane.

An elliptical (or oval) cross-sectional shape of the light immediatelyafter it is emitted from each of the light source sections can thus bechanged to a substantially circular shape, whereby the image displaycharacteristics can be improved.

In the image display apparatus according to the aspect of the invention,it is preferable that a light exiting surface of the prism is a lightcollecting lens surface.

In this way, when an image is displayed on an object located in aposition in the vicinity of the focal point of the lens surface, betterimage display characteristics are provided.

In the image display apparatus according to the aspect of the invention,it is preferable that the angle of radiation of the light outputted fromeach of the plurality of light source sections in the direction of thenormal to the first plane is greater than the angle of radiation of theoutputted light in the in-plane direction in the first plane.

The contour of the intensity distribution of a laser light emitted froma semiconductor laser, which is typically used as a light source, has asubstantially elliptical shape. That is, the angle of radiation of thelaser light in the direction of the major axis of the ellipse differsfrom the angle of radiation of the laser light in the direction of theminor axis of the ellipse. For example, setting the direction of themajor axis, where the angle of radiation is larger, to be perpendicularto the first plane allows the prism to be obliquely disposed in thefirst plane, whereby the size of the apparatus can be reduced.

A head-mounted display according to another aspect of the inventionincludes a light reflection member that reflects at least part of lightincident thereon, and an image display apparatus that irradiates lightto the light reflection member, the image display apparatus including aplurality of light source sections each of which outputs a light, alight combining section that combines the light from the plurality oflight source sections, and an optical scan section that deflects thecombined light from the light combining section for two-dimensionalscanning around a first axis and a second axis perpendicular to thefirst axis, wherein the optical axis of the light outputted from each ofthe plurality of light source sections and directed through the lightcombining section toward the optical scan section is present in a firstplane, the optical scan section includes a base that swings around thefirst axis and the second axis, a light reflection plate having a lightreflection surface that reflects the light from the light combiningsection, the light reflection surface having an area larger than thearea of the base, and a spacer that connects the base and the lightreflection plate to each other, the first axis is present in the firstplane, the second axis is parallel to a normal to the first plane, andthe light reflection surface is configured to be perpendicular to thefirst plane when the optical scan section is not driven.

A head-mounted display formed of a reduced number of parts can thus beprovided.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described with reference to the accompanyingdrawings, wherein like numbers reference like elements.

FIG. 1 is a plan view showing an image display apparatus according to apreferred embodiment of the invention.

FIG. 2 is a cross-sectional view of a laser light emitted from eachlaser light source shown in FIG. 1.

FIG. 3 is a side view of the image display apparatus shown in FIG. 1.

FIG. 4 is a plan view showing an optical scan section (optical scanner)provided in the image display apparatus shown in FIG. 1.

FIG. 5 is a cross-sectional view of the optical scanner shown in FIG. 4.

FIG. 6 is a block diagram of a voltage applying section provided in theoptical scanner shown in FIG. 4.

FIGS. 7A and 7B show examples of voltages generated by a first voltagegenerator and a second voltage generator shown in FIG. 6.

FIGS. 8A and 8B show a difference in a drawable region caused by thedisposition of the optical scanner.

FIG. 9 is a perspective view showing a heads-up display based on theimage display apparatus according to the embodiment of the invention.

FIG. 10 is a perspective view showing a head-mounted display accordingto an embodiment of the invention.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

An image display apparatus and a head-mounted display according topreferred embodiments of the invention will be described below withreference to the accompanying drawings.

1. Image Display Apparatus

FIG. 1 is a plan view showing an image display apparatus according to apreferred embodiment of the invention. FIG. 2 is a cross-sectional viewof a laser light emitted from each laser light source shown in FIG. 1.FIG. 3 is a side view of the image display apparatus shown in FIG. 1.FIG. 4 is a plan view showing an optical scan section (optical scanner)provided in the image display apparatus shown in FIG. 1. FIG. 5 is across-sectional view of the optical scanner shown in FIG. 4. FIG. 6 is ablock diagram of a voltage applying section provided in the opticalscanner shown in FIG. 4. FIGS. 7A and 7B show examples of voltagesgenerated by a first voltage generator and a second voltage generatorshown in FIG. 6. FIGS. 8A and 8B show a difference in a drawable regioncaused by the disposition of the optical scanner. In the followingdescription, the upper side in FIG. 5 is called “upper” and the lowerside in FIG. 5 is called “lower” for ease of description. Further, threeaxes perpendicular to one another are called an X axis, a Y axis, and aZ axis, as shown in FIG. 1.

The image display apparatus 1 shown in FIG. 1 is an apparatus that scansan object 10, such as a screen and a wall surface, with light to displayan image.

The image display apparatus 1 includes a drawing light source unit 2,which outputs drawing laser light LL, a prism 3 (optical member), whichinclines the optical axis of the drawing laser light LL and deforms thetransverse cross-sectional shape of the drawing laser light LL, anoptical scan section 4, which deflects the drawing laser light LL havingpassed through the prism 3 for scanning, a detector 5, which detects theintensity of the drawing laser light LL, and a controller 6, whichcontrols the operation of the drawing light source unit 2 and theoptical scan section 4.

The image display apparatus 1 has an enclosure 9, which has a flat shapehaving relatively large dimensions in the XY plane and a height in theZ-axis direction, and the enclosure 9 accommodates the drawing lightsource unit 2, the prism 3, the optical scan section 4, and the detector5 arranged in the XY plane. The enclosure 9 in the present embodimenthas a substantially rectangular exterior shape in a plan view in thethickness direction of the enclosure 9. The enclosure 9 has a window 91formed, for example, of a transparent member (made, for example, ofglass or plastic), through which the drawing laser light LL deflected bythe optical scan section 4 for scanning exits out of the enclosure 9.The controller 6 may be accommodated in the enclosure 9 as in thepresent embodiment or may be provided externally to the enclosure 9.

The above components will be sequentially described below.

1-1. Drawing Light Source Unit

The drawing light source unit 2 includes laser light sources (lightsource sections) 21R, 21G, and 21B for the following colors: red; green;and blue and collimator lenses 22R, 22G, and 22B and dichroic mirrors23R, 23G, and 23B provided in correspondence with the laser lightsources 21R, 21G, and 21B, as shown in FIG. 1.

Each of the laser light sources 21R, 21G, and 21B has a light source anda drive circuit (not shown). The laser light source 21R emits a redlaser light RR. The laser light source 21G emits a green laser light GG.The laser light source 21B emits a blue laser light BB. The laser lightRR, GG, and BB are emitted in accordance with drive signals transmittedfrom the controller 6 and are parallelized or substantially parallelizedby the collimator lenses 22R, 22G, and 22B, respectively.

In the present embodiment, the laser light sources 21R, 21G, and 21B arearranged in the −Y-axis direction in the order of the laser light source21R, the laser light source 21B, and the laser light source 21G anddisposed in the enclosure 9 in a left end portion thereof in FIG. 1. Thelaser light sources 21R, 21G, and 21B emit the laser light RR, GG, andBB, respectively, in the +X-axis direction. The thus arranged laserlight sources 21R, 21G, and 21B occupy a relatively small space,allowing the size of the image display apparatus 1 (enclosure 9) to bereduced. It is noted that the arrangement of the laser light sources21R, 21G, and 21B is not limited to the arrangement described above.

Each of the laser light sources 21R, 21G, and 21B can, for example, bean edge-emitting semiconductor laser, a surface-emitting semiconductorlaser, or any other suitable semiconductor laser. Using a semiconductorlaser allows the size of each of the laser light sources 21R, 21G, and21B to be reduced.

When each of the laser light sources 21R, 21G, and 21B is formed of asemiconductor laser, the optical intensity distribution of each of thelaser light RR, GG, and BB emitted from the laser light sources 21R,21G, and 21B has in general a contour (called an FFP: far field pattern)having a substantially elliptical shape. It is assumed in the followingdescription that the “cross-sectional shape” of each of the laser lightRR, GG, and BB has the same meaning as that of the “contour of theoptical intensity distribution” of the corresponding one of the laserlight RR, GG, and BB. That is, in this case, each of the laser lightsRR, GG, and BB emitted from the laser light sources 21R, 21G, and 21Bhas a substantially elliptical cross-sectional shape. Thecross-sectional shape used herein is the shape of a cross sectionperpendicular to the optical axis of each of the laser light RR, GG, andBB.

The laser light sources 21R, 21G, and 21B emit the laser light RR, GG,and BB, respectively, each of which has a substantially elliptical(oval) cross-sectional shape, as shown in FIG. 2. Each of the laserlight sources 21R, 21G, and 21B is disposed in the enclosure 9 so thatthe major axis of the ellipse substantially coincides with the Z axisand the minor axis of the ellipse substantially coincides with the Yaxis (XY plane). In other words, each of the laser light RR, GG, and BBemitted from the laser light sources 21R, 21G, and 21B has an angle ofradiation in the Z-axis direction (the direction of a normal to the XYplane) greater than the angle of radiation in the Y-axis direction (thein-plane direction in the XY plane). In this case, the three laser lightsources 21R, 21G, and 21B can be arranged in the Y-axis direction atnarrower intervals than, for example, in a case where the angles ofradiation are configured in a reversed manner (in a case where the angleof radiation in the Z-axis direction is smaller than the angle ofradiation in the Y-axis direction), whereby the dimensions of theenclosure 9 in the XY plane can be reduced. The size of the imagedisplay apparatus 1 can therefore be reduced.

Each of the laser lights RR, GG, and BB emitted from the laser lightsources 21R, 21G, and 21B is linearly polarized light. Further, thelaser light RR, GG, and BB are s-polarized light, which is a lightcomponent polarized in a direction perpendicular to thereflection/transmission surfaces (light incident surfaces) of thedichroic mirrors 23R, 23G, and 23B and the light incident surface of theprism 3. That is, each of the laser lights RR, GG, and BB emitted fromthe laser light sources 21R, 21G, and 21B is polarized light oscillating(polarized) in the Z-axis direction and has an ellipticalcross-sectional shape the major axis of which coincides with theoscillating direction. When each of the laser lights RR, GG, and BB iss-polarized light, the amount of loss of the laser light RR, GG, and BBproduced when they are incident on the dichroic mirrors 23R, 23G, and23B and the prism 3, can be reduced.

The dichroic mirror 23R is characterized in that it reflects the laserlight RR. The dichroic mirror 23B is characterized in that it reflectsthe laser light BB and transmits the laser light RR. The dichroic mirror23G is characterized in that it transmits the laser light GG andreflects the laser light RR and BB. The dichroic mirrors 23R, 23G, and23B cause the optical axes of the color laser light RR, GG, and BB tocoincide or substantially coincide (be combined) with one another sothat the single drawing laser light LL is outputted in the +X-axisdirection. That is, the dichroic mirrors 23R, 23G, and 23B form a lightcombining section 23, which combines the laser light RR, GG, and BB withone another.

In the present embodiment, the dichroic mirror 23R, the dichroic mirror23B, and the dichroic mirror 23G are arranged in this order in the−Y-axis direction in correspondence with the arrangement of the laserlight sources 21R, 21B, and 21G. The dichroic mirror 23R is disposed sothat it reflects the laser light RR emitted in the +X-axis directionfrom the laser light source 21R and causes the reflected light to travelin the −Y-axis direction. The dichroic mirror 23B is disposed so that itnot only reflects the laser light BB emitted in the +X-axis directionfrom the laser light source 21B and causes the reflected light to travelin the −Y-axis direction but also transmits the laser light RR reflectedoff the dichroic mirror 23R in the −Y-axis direction. Further, thedichroic mirror 23G is disposed so that it not only transmits the laserlight GG emitted in the +X-axis direction from the laser light source21G but also reflects the laser light RR and BB reflected in the −Y-axisdirection off the dichroic mirrors 23R and 23B and causes the reflectedlight to travel in the +X-axis direction. The thus configured lightcombining section 23 outputs the drawing laser light LL in the +X-axisdirection.

The dichroic mirrors 23R, 23G, and 23B are preferably disposed so that alaser light of a shorter wavelength is incident on the prism 3 at agreater angle of incidence in consideration of the dispersion resultingfrom the difference in the refractive index among the wavelengths of thelaser light. That is, the dichroic mirrors 23R, 23G, and 23B aredisposed with their reflection surfaces slightly shifted from oneanother around the Z axis so that the following relationship issatisfied: the angle of incidence θ_(B) of the blue laser light BB>theangle of incidence θ_(G) of the green laser light GG>the angle ofincidence θ_(R) of the red laser light RR.

1-2. Prism

The prism 3 is an optical member having a first function of incliningthe optical axis of the drawing laser light LL, a second function ofdeforming the shape (cross-sectional shape) of the drawing laser lightLL, and a third function of controlling the angle of radiation of thedrawing laser light LL (collecting drawing laser light LL, for example).The prism 3 is a substantially colorless, transparent polyhedron made ofglass or quartz. The prism 3 is not limited to any specific type as longas it has the functions described above and can, for example, be atriangular prism having a substantially triangular columnar shape. Theangled portions of the triangular prism may, for example, be chamferedor otherwise rounded as long as the resultant shape does not affect thefunctions.

The first function will be described first. The prism 3 receives thedrawing laser light LL incident through a light incident surface 31 andoutputs the drawing laser light LL through a light exiting surface 32 ina direction inclined to the +X-axis direction toward the +Y-axisdirection (a direction toward the inner portion of enclosure 9). Thatis, the prism 3 inclines the optical axis of the drawing laser light LLaround the Z axis (in XY plane). The thus configured prism 3 can directthe drawing laser light LL toward an inner portion of the enclosure 9.The enclosure 9 has a space large enough to place members alongextensions of the optical axes of the light emitted from the laser lightsources 21R and 21B, and the internal space of the enclosure 9 can beefficiently used by placing the optical scan section 4 in the space.That is, inclining the optical axis of the drawing laser light LL towardan inner portion of the enclosure 9 can reduce the volume of a deadspace (unused space where no member is disposed) in the enclosure 9,whereby the size of the image display apparatus 1 can be reduced.

The second function described above will be described next. The prism 3changes the cross-sectional shape of the drawing laser light LL that isperpendicular to the optical axis thereof from the substantiallyelliptical shape to a substantially circular shape. Specifically, theprism 3 changes the cross-sectional shape of the drawing laser light LLto a substantially circular shape by increasing the width of thecross-sectional shape of the incident drawing laser light LL in thedirection in which the XY plane extends with the width thereof in theZ-axis direction substantially unchanged. In other words, the prism 3changes the cross-sectional shape of the drawing laser light LL in sucha way that the length of the minor axis of the ellipticalcross-sectional shape is increased to a point where the ratio betweenthe minor axis and the major axis (aspect ratio) is substantially one.When the cross-sectional shape of the drawing laser light LL becomes asubstantially circular shape as described above, the image displayapparatus 1 can provide excellent image display characteristics.Further, when the cross-sectional shape of the drawing laser light LLbefore it is incident on the prism 3 has a substantially ellipticalshape the major axis of which extends in the Z-axis direction asdescribed above, the prism 3 only needs to be angularly shifted in theXY plane, whereby the prism 3 can be disposed so that the length of theenclosure 9 in the thickness direction (Z-axis direction) correspondingto the space where the prism 3 occupies is minimized. As a result, thesize (thickness) of the image display apparatus 1 can be reduced.

The third function described above will be described next. The lightexiting surface 32 of the prism 3 is formed of a curved convex surface(lens surface) and hence functions as a collector lens that collects(focuses) the drawing laser light LL incident in the form ofparallelized light on the prism 3. Focusing the drawing laser light LLas described above can increase the sharpness of an image displayed onthe object 10 located in a position in the vicinity of the focal point(form an image having higher resolution). Further, the light exitingsurface 32 having a function of a collector lens eliminates thenecessity of separately providing a collector lens in addition to theprism 3, whereby the number of parts can be reduced and the size of theimage display apparatus 1 can be reduced. The light exiting surface 32of the prism 3 is not limited to a convex surface (collector lens) aslong as the light exiting surface 32 can control the angle of radiationof the light that exits through the light exiting surface 32 and can,for example, be a concave surface (a lens that causes light to diverge).

The image display apparatus 1, which uses the prism 3 as the opticalmember, does not necessarily use a prism but may use an optical membercapable of providing the same functions as those provided by the prism 3described above.

The drawing light source unit 2 and the prism 3 have been described indetail. In the image display apparatus 1, the optical axes of the laserlight RR, GG, and BB (drawing laser light LL) are present in the same XYplane (first plane F), as shown in FIG. 3. That is, the followingactions are made in the plane F: The laser light sources 21R, 21G, and21B emit the laser light RR, GG, and BB; the light combining section 23combines the laser light RR, GG, and BB and outputs the resultantdrawing laser light LL; and the prism. 3 inclines the optical axis ofthe drawing laser light LL in the XY plane.

1-3. Optical Scan Section

The optical scan section 4 has a function of deflecting the drawinglaser light LL having passed through the prism 3 for two-dimensionalscanning. The optical scan section 4 is not limited to a specific typeand can be any device capable of deflecting the drawing laser light LLfor two-dimensional scanning. For example, an optical scanner 40 havingthe following configuration can be used.

The optical scanner 40 includes a movable portion 41, a pair of shafts421 and 422 (first shafts), a frame 43, two pairs of shafts 441, 442,443, and 444 (second shafts), a support 45, a permanent magnet 46, acoil 47, a magnet core 48, and a voltage applying section 49, as shownin FIGS. 4 and 5.

Among the components described above, the movable portion 41 and thepair of shafts 421 and 422 form a first oscillation system that swings(makes reciprocating motion) around a first axis J1 by using the shafts421 and 422 as axes. Further, the movable portion 41, the pair of shafts421 and 422, the frame 43, the two pairs of shafts 441, 442, 443, and444, and the permanent magnet 46 form a second oscillation system thatswings (makes reciprocating motion) around a second axis J2. Thepermanent magnet 46, the coil 47, and the voltage applying section 49form a driver that drives the first and second oscillation systemsdescribed above.

The components of the optical scanner 40 will be sequentially describedbelow in detail.

The movable portion 41 includes abase 411 and a light reflection plate413 fixed to the base 411 via a spacer 412, as shown in FIGS. 4 and 5. Alight reflection portion 414, which reflects light, is provided on theupper surface (one surface) of the light reflection plate 413. Thesurface of the light reflection portion 414 forms a light reflectionsurface 414 a, which reflects the drawing laser light LL. The movableportion 41 swings around the first axis J1 and the second axis J2, asdescribed above. That is, it can be said that the base 411, the spacer412, the light reflection plate 413, and the light reflection surface414 a, which form the movable portion 41, also swing around the firstaxis J1 and the second axis J2.

The light reflection plate 413 is disposed so that it is set apart fromthe base 411 and the shafts 421 and 422 via the spacer 412 in thethickness direction of the light reflection plate 413 but overlaps withthe shafts 421 and 422 when viewed in the thickness direction(hereinafter also referred to as a “plan view”).

The configuration described above allows the area of the plate surfaceof the light reflection plate 413 to be increased while the distancebetween the shaft 421 and the shaft 422 to be shortened. Further, sincethe distance between the shaft 421 and the shaft 422 can be shortened,the size of the frame 43 can be reduced. Moreover, since the size of theframe 43 can be reduced, the distance between the shafts 441, 442 andthe shafts 443, 444 can be shortened. As a result, the size of theoptical scanner 40 can be reduced even with the area of the platesurface of the light reflection plate 413 increased. That is, the lightreflection plate 413 can be enlarged so that the resolution can beincreased, whereas the size of the optical scanner 40 is reduced.

The light reflection plate 413 is further formed so that it covers theentire shafts 421 and 422 in the plan view. In other words, the shafts421 and 422 are located inside the outer circumference of the lightreflection plate 413 in the plan view. The area of the plate surface ofthe light reflection plate 413 is thus increased, resulting in anincrease in the area of the light reflection portion 414. Theconfiguration further prevents unwanted light (light that has not beenincident on light reflection plate 413, for example) from beingreflected off the shafts 421 and 422 to form stray light.

The light reflection plate 413 is further formed so that it covers theentire frame 43 in the plan view. In other words, the frame 43 islocated inside the outer circumference of the light reflection plate 413in the plan view. The area of the plate surface of the light reflectionplate 413 is thus increased, resulting in an increase in the area of thelight reflection portion 414. The configuration further prevents theunwanted light from being reflected off the frame 43 to form straylight.

Further, the light reflection plate 413 is formed so that it covers theentire shafts 441, 442, 443, and 444 in the plan view. The area of theplate surface of the light reflection plate 413 is thus increased,resulting in an increase in the area of the light reflection portion414. The configuration further prevents the unwanted light from beingreflected off the shafts 441, 442, 443, and 444 to form stray light.

In the present embodiment, the light reflection plate 413 has a circularshape in the plan view. The light reflection plate 413 does notnecessarily have a circular shape and can, for example, have anelliptical shape or a rectangular or any other polygonal shape in theplan view.

The thus shaped light reflection plate 413 has a hard layer 415 providedon the lower surface thereof (the other surface, the surface of thelight reflection plate 413 that faces the base 411).

The hard layer 415 is made of a material harder than the material ofwhich the body of the light reflection plate 413 is made, whereby therigidity of the light reflection plate 413 can be increased. The thusincreased rigidity prevents the light reflection plate 413 from beingbent or suppresses the amount of bending when the light reflection plate413 swings. The thickness of the light reflection plate 413 can also bereduced, whereby the moment of inertia of the light reflection plate 413around the first and second axes J1, J2 can be reduced when the lightreflection plate 413 swings therearound.

The material of which the hard layer 415 is made is not limited to aspecific one and can be any material harder than the material of whichthe body of the light reflection plate 413 is made, for example,diamond, quartz, sapphire, lithium tantalate, potassium niobate, or acarbon nitride film. It is particularly preferable to use diamond. Thehard layer 415 is provided as necessary and can be omitted.

The lower surface of the light reflection plate 413 is fixed to the base411 via the spacer 412. The light reflection plate 413 can thereforeswing around the first axis J1 without the lower surface of the lightreflection plate 413 coming into contact with the shafts 421, 422, theframe 43, or the shafts 441, 442, 443, 444.

Further, the base 411 is located inside the outer circumference of thelight reflection plate 413 in the plan view. Moreover, the area of thebase 411 in the plan view is preferably minimized to the extent that thebase 411 can support the light reflection plate 413 via the spacer 412.In this case, the distance between the shaft 421 and the shaft 422 canbe reduced, while the area of the plate surface of the light reflectionplate 413 is increased.

The frame 43, which has a frame-like shape, is disposed so that itsurrounds the base 411 of the movable portion 41 described above. Inother words, the base 411 of the movable portion 41 is disposed insidethe frame 43, which has a frame-like shape. The frame 43 is supported bythe support 45 via the shafts 441, 442, 443, and 444. The base 411 ofthe movable portion 41 is supported by the frame 43 via the shafts 421and 422.

The length of the frame 43 in the direction along the first axis J1 islonger than the length thereof in the direction along the second axisJ2. That is, a>b is satisfied, where “a” represents the length of theframe 43 in the direction along the first axis J1, and “b” representsthe length of the frame 43 in the direction along the second axis J2.The length of the optical scanner 40 in the direction along the secondaxis J2 can therefore be reduced, while the length necessary for theshafts 421 and 422 is ensured. Since the optical scanner 40 is disposedin the enclosure 9 so that the second axis J2 is parallel to the Z axisas described later, the thickness of the enclosure 9 (length in Z-axisdirection) can be reduced when the relationship a>b is satisfied asdescribed above.

Further, the frame 43 has a shape that follows the exterior shape of astructure formed of the base 411 of the movable portion 41 and the pairof shafts 421 and 422 in the plan view. The thus shaped frame 43 can becompact while allowing the first oscillation system formed of themovable portion 41 and the pair of shafts 421 and 422 to oscillate, thatis, the movable portion 41 to swing around the first axis J1. The shapeof the frame 43 is not limited to the illustrated shape and can be anyframe-like shape.

Each of the shafts 421 and 422 and the shafts 441, 442, 443, and 444 iselastically deformable. The shafts 421 and 422 connect the movableportion 41 to the frame 43 in such away that the movable portion 41 isrotatable (e.g., pivotable) around the first axis J1. Further, theshafts 441, 442, 443, and 444 connect the frame 43 to the support 45 insuch a way that the frame 43 is rotatable around the second axis J2,which is perpendicular to the first axis J1.

The shafts 421 and 422 are disposed on opposite sides of the base 411 ofthe movable portion 41. Further, each of the shafts 421 and 422 has anelongated shape extending in the direction along the first axis J1. Eachof the shafts 421 and 422 has one end connected to the base 411 and theother end connected to the frame 43. Each of the shafts 421 and 422 isfurther disposed so that the central axis thereof coincides with thefirst axis J1. The thus configured shafts 421 and 422 are torsionallydeformed when the movable portion 41 swings around the first axis J1.

The shafts 441, 442 and the shafts 443, 444 are disposed on oppositesides to each other via the frame 43. Each of the shafts 441, 442, 443,and 444 has an elongated shape extending in the direction along thesecond axis J2. Further, each of the shafts 441, 442, 443, and 444 hasone end connected to the frame 43 and the other end connected to thesupport 45. Further, the shafts 441 and 442 are disposed on oppositesides to each other via the second axis J2. Similarly, the shafts 443and 444 are disposed on opposite sides to each other via the second axisJ2. The shafts 441, 442, 443, and 444 are configured so that the shafts441 and 442 as a whole and the shafts 443 and 444 as a whole aretorsionally deformed when the frame 43 swings around the second axis J2.

As described above, the movable portion 41 rotatable around the firstaxis J1 and the frame 43 rotatable around the second axis J2 allow themovable portion 41 (that is, light reflection plate 43) to swing aroundthe two axes perpendicular to each other, the first and second axes J1,J2.

The shapes of the shafts 421 and 422 and the shafts 441, 442, 443, and444 are not limited to those described above, and each of them may, forexample, have a bent or curved portion or a branch in at least oneposition along the shaft.

The base 411, the shafts 421 and 422, the frame 43, the shafts 441, 442,443, and 444, and the support 45 described above are formed integrallywith one another.

In the present embodiment, the base 411, the shafts 421 and 422, theframe 43, the shafts 441, 442, 443, and 444, and the support 45 areformed by etching an SOI substrate formed of a first Si layer (devicelayer), an SiO₂ layer (box layer), and a second Si layer (handle layer)stacked in this order. The configuration described above provides thefirst and second oscillation systems with excellent oscillationcharacteristics. Further, forming the base 411, the shafts 421 and 422,the frame 43, the shafts 441, 442, 443, and 444, and the support 45 byusing the SOI substrate, which allows etching-based micro-processing,not only provides excellent precision in their dimensions but alsoreduces the size of the optical scanner 40.

The first Si layer of the SOI substrate forms the base 411, the shafts421, and 422, and the shafts 441, 442, 443, and 444. The shafts 421 and422 and the shafts 441, 442, 443, and 444 therefore have excellentelasticity. Further, the base 411 will not come into contact with theframe 43 when the base 411 pivots around the first axis J1.

Each of the frame 43 and the support 45 is formed of the SOI substrateor the stacked member formed of the first Si layer, the SiO₂ layer, andthe second Si layer, whereby the frame 43 and the support 45 haveexcellent rigidity. Further, the SiO₂ layer and the second Si layer ofthe frame 43 not only function as a rib that increases the rigidity ofthe frame 43 but also have a function of preventing the movable portion41 from coming into contact with the permanent magnet 46.

The upper surface of each of the shafts 421 and 422, the shafts 441,442, 443, and 444, the frame 43, and the support 45, which are locatedoutside the light reflection plate 413 in the plan view, preferablyundergoes antireflection processing, which prevents unwanted lightincident on portions other than the light reflection plate 413 fromforming stray light. The antireflection processing is not limited to aspecific process and can, for example, be formation of an antireflectionfilm (dielectric multilayer film), surface roughing, and surfaceblackening.

The materials of which the base 411, the shafts 421 and 422, and theshafts 441, 442, 443, and 444 are made and the method for forming thesecomponents described above are presented by way of example and are notnecessarily used in the invention.

Further, in the present embodiment, the spacer 412 and the lightreflection plate 413 are also formed by etching the SOI substrate. Thespacer 412 is formed of a stacked member of the SiO₂ layer and thesecond Si layer of the SOI substrate. The light reflection plate 413 isformed of the first Si layer of the SOI substrate. The spacer 412 andthe light reflection plate 413 bonded to each other can thus bemanufactured in a simple, highly precise manner by forming the spacer412 and the light reflection plate 413 based on the SOI substrate asdescribed above.

The spacer 412 is bonded to the base 411 with an adhesive, a waxmaterial, or any other suitable bonding material (not shown).

The permanent magnet 46 is bonded to the lower surface of the frame 43described above. A method for bonding the permanent magnet 46 to theframe 43 is not limited to a specific one and can be, for example, abonding method using an adhesive. The permanent magnet 46 is magnetizedin a direction inclined to the first and second axes J1, J2 in the planview.

In the present embodiment, the permanent magnet 46 has an elongatedshape (rod-like shape) extending in a direction inclined to the firstand second axes J1, J2. The permanent magnet 46 is magnetized in theelongated direction. That is, the permanent magnet 46 is magnetized sothat one end thereof forms an S pole and the other end thereof forms anN pole. Further, the permanent magnet 46 is disposed so that it issymmetrical with respect to the intersection of the first axis J1 andthe second axis J2 in the plan view.

The inclination angle θ of the direction in which the permanent magnet46 is magnetized (direction in which permanent magnet 46 extends) withrespect to the second axis J2 is not limited to a specific value but ispreferably greater than or equal to 30° but smaller than or equal to60°, more preferably greater than or equal to 45° but smaller than orequal to 60°, still more preferably 45°. The thus disposed permanentmagnet 46 allows the movable portion 41 to swing around the second axisJ2 in a smooth, reliable manner.

The permanent magnet 46 can preferably be, for example, a neodymiummagnet, a ferrite magnet, a samarium cobalt magnet, an Alnico magnet, ora bonded magnet. The permanent magnet 46 is a magnetized hard magneticmaterial and formed, for example, by placing a hard magnetic materialnot yet having been magnetized on the frame 43 and magnetizing theentire structure. The reason for this is that an attempt to place thepermanent magnet 46, which has been magnetized, on the frame 43 may notresult in successful placement of the permanent magnet 46 in a desiredposition in some cases because magnetic fields produced by objectsoutside the apparatus and other parts in the apparatus affect theplacement of the permanent magnet 46.

The coil 47 is disposed immediately below the permanent magnet 46,whereby a magnetic field produced by the coil 47 can act on thepermanent magnet 46 in an efficient manner. As a result, the powerconsumption and the size of the optical scanner 40 can be reduced. Thecoil 47 is wound around the magnetic core 48. The magnetic fieldproduced by the coil 47 can thus act on the permanent magnet 46 in anefficient manner. The magnetic core 48 may be omitted.

The thus configured coil 47 is electrically connected to the voltageapplying section 49. When the voltage applying section 49 applies avoltage to the coil 47, the coil 47 produces a magnetic field having amagnetic perpendicular to the first and second axes J1, J2.

The voltage applying section 49 includes a first voltage generator 491that generates a first voltage V1 for causing the movable portion 41 topivot around the first axis J1, a second voltage generator 492 thatgenerates a second voltage V2 for causing the movable portion 41 topivot around the second axis J2, and a voltage superimposing section 493that superimposes the first voltage V1 and the second voltage V2 on eachother, and the superimposed voltage from the voltage superimposingsection 493 is applied to the coil 47, as shown in FIG. 6.

The first voltage V1 (voltage for primary scan), which is generated bythe first voltage generator 491, periodically changes at a period T1, asshown in FIG. 7A. The first voltage V1 has a sinusoidal waveform. Thefrequency of the first voltage V1 (1/T1) is preferably a value ranging,for example, from 10 to 40 kHz. In the present embodiment, the frequencyof the first voltage V1 is set to be equal to a torsional resonantfrequency (f1) of the first oscillation system formed of the movableportion 41 and the pair of shafts 421 and 422, whereby the angle ofpivotal motion of the movable portion 41 around the first axis J1 can beincreased.

On the other hand, the second voltage V2 (voltage for secondary scan),which is generated by the second voltage generator 492, periodicallychanges at a period T2 different from the period T1, as shown in FIG.7B. The second voltage V2 has a saw-toothed waveform. The frequency ofthe second voltage V2 (1/T2) only needs to differ from the frequency ofthe first voltage V1 (1/T1) and is preferably a value ranging, forexample, from 30 to 80 Hz (about 60 Hz). In the present embodiment, thefrequency of the second voltage V2 is adjusted to be a frequencydifferent from a torsional resonant frequency (resonant frequency) ofthe second oscillation system formed of the movable portion 41, the pairof shafts 421 and 422, the frame 43, the two pairs of shafts 441, 442,443, and 444, and the permanent magnet 46.

The thus set frequency of the second voltage V2 is preferably lower thanthe frequency of the first voltage V1. In this case, the movable portion41 is allowed to swing not only around the first axis J1 at thefrequency of the first voltage V1 but also around the second axis J2 atthe frequency of the second voltage V2 in a more reliable, smoothermanner.

Now, let f1 [Hz] be the torsional resonant frequency of the firstoscillation system and f2 [Hz] be the torsional resonant frequency ofthe second oscillation system, and f1 and f2 preferably satisfy f2<f1,more preferably 10×f2≦f1. Satisfying the relationship described aboveallows the movable portion 41 to pivot not only around the first axis J1at the frequency of the first voltage V1 but also around the second axisJ2 at the frequency of the second voltage V2 in a smoother manner. Onthe other hand, when f1≦f2, the first oscillation system can oscillateat the frequency of the second voltage V2.

The thus configured first voltage generator 491 and second voltagegenerator 492 are connected to the controller 6 and driven based onsignals from the controller 6. The voltage superimposing section 493 isconnected to the first voltage generator 491 and the second voltagegenerator 492.

The voltage superimposing section 493 includes an adder 493 a forapplying a voltage to the coil 47. The adder 493 a receives the firstvoltage V1 from the first voltage generator 491, receives the secondvoltage V2 from the second voltage generator 492, superimposes thevoltages on each other, and applies the resultant voltage to the coil47.

A description will next be made of a method for driving the opticalscanner 40. It is assumed that the frequency of the first voltage V1 isset to be equal to the torsional resonant frequency of the firstoscillation system, and that the frequency of the second voltage V2 isset to be not only different from the torsional resonant frequency ofthe second oscillation system but also smaller than the frequency of thefirst voltage V1 (for example, the frequency of the first voltage V1 isset at 15 kHz, and the frequency of the second voltage V2 is set at 60Hz).

For example, when the voltage superimposing section 493 superimposes thefirst voltage V1 shown in FIG. 7A and the second voltage V2 shown inFIG. 7B on each other and applies the superimposed voltage to the coil47, the first voltage V1 produces the following alternately switchingmagnetic fields: a magnetic field that causes one end (N pole) of thepermanent magnet 46 to be attracted to the coil 47 and the other end (Spole) of the permanent magnet 46 to be repulsed from the coil 47 (themagnetic field is referred to as a “magnetic field A1”); and a magneticfield that causes the one end (N pole) of the permanent magnet 46 to berepulsed from the coil 47 and the other end (S pole) of the permanentmagnet 46 to be attracted to the coil 47 (the magnetic field is referredto as a “magnetic field A2”).

When the magnetic field A1 and the magnetic field A2 are alternatelyswitched from each other as described above, oscillation having atorsional oscillation component around the first axis J1 is excited inthe frame 43, and the oscillation causes the shafts 421 and 422 to betorsionally deformed and hence the movable portion 41 to swing aroundthe first axis J1 at the frequency of the first voltage V1. Since thefrequency of the first voltage V1 is equal to the torsional resonantfrequency of the first oscillation system, the resonant oscillationallows the movable portion 41 to swing at a large amplitude.

On the other hand, the second voltage V2 produces the followingalternately switching magnetic fields: a magnetic field that causes theone end (N pole) of the permanent magnet 46 to be attracted to the coil47 and the other end (S pole) of the permanent magnet 46 to be repulsedfrom the coil 47 (the magnetic field is referred to as a “magnetic fieldB1”); and a magnetic field that causes the one end (N pole) of thepermanent magnet 46 to be repulsed from the coil 47 and the other end (Spole) of the permanent magnet 46 to be attracted to the coil 47 (themagnetic field is referred to as a “magnetic field B2”).

When the magnetic field B1 and the magnetic field B2 are alternatelyswitched from each other as described above, the shafts 441, 442 and theshafts 443, 444 are torsionally deformed and the frame 43 along with themovable portion 41 swings around the second axis J2 at the frequency ofthe second voltage V2. Since the frequency of the second voltage V2 isset to be much lower than the frequency of the first voltage V1 and thetorsional resonant frequency of the second oscillation system is set tobe lower than the torsional resonant frequency of the first oscillationsystem as described above, the pivotal motion of the movable portion 41around the first axis J1 will not occur at the frequency of the secondvoltage V2.

As described above, when the first voltage V1 and the second voltage V2superimposed on each other are applied to the coil 47 in the opticalscanner 40, the movable portion 41 can pivot not only around the firstaxis J1 at the frequency of the first voltage V1 but also around thesecond axis J2 at the frequency of the second voltage V2. The thusconfigured optical scanner 40 allows the cost and size of the apparatusto be reduced and causes the movable portion 41 to swing around thefirst and second axes J1, J2 based on the electro-magnetic drive method(moving magnet method), whereby the drawing laser light LL reflected offthe light reflection portion 414 can be deflected for two-dimensionalscanning. Further, since the number of parts that form the drive source(permanent magnet and coil) can be reduced, the resultant configurationcan be simple and compact. Moreover, since the coil 47 is set apart fromthe oscillation systems of the optical scanner 40, heat generated by thecoil 47 will not adversely affect the oscillation systems.

The configuration of the optical scanner 40 has been described above indetail. According to the gimbal-type, two-dimensional-scanning opticalscanner 40 described above, which is alone capable of deflecting thedrawing laser light LL for two-dimensional scanning, the size of theoptical scan section 4 can be reduced and alignment adjustment thereofcan be readily made as compared, for example, with a configuration inwhich two one-dimensional-scanning optical scanners are combined witheach other to deflect the drawing laser light LL for two-dimensionalscanning.

The optical scanner 40 is an electro-magnetically driven optical scannerdriven by using the permanent magnet 46 and the coil 47. The thusconfigured optical scanner 40 requires the permanent magnet 46 and thecoil 47 to face each other as shown in FIG. 5, which increases thethickness of the optical scanner 40 (length in the direction of an axisJ3 that intersects the intersection of the first and second axes J1, J2and is perpendicular to the two axes). However, the size of the opticalscanner 40 in the in-plane direction in the plane including the firstand second axes J1, J2 can be reduced. As described above, the opticalscanner 40, the size of which in the in-plane direction described aboveis reduced instead of the size in the thickness direction, forms anoptical scanner suitable for the image display apparatus 1.

The optical scanner 40 having the configuration described above isdisposed in the enclosure 9 so that the light reflection portion 414 isperpendicular to the XY plane when the optical scanner 40 is not driven(when no voltage is applied to the coil 47) as shown in FIGS. 1 and 3.In other words, the optical scanner 40 is disposed in the enclosure 9 sothat the plane including the first and second axes J1, J2 isperpendicular to the XY plane (the axis J3 is present in the plane F).Since the optical scanner 40 has a small size in the in-plane directionin the plane including the first and second axes J1, J2 as describedabove, disposing the optical scanner 40 as described above allows thesize (thickness) of the image display apparatus 1 (enclosure 9) to bereduced. Since the optical scanner 40 is not so thin in the direction ofthe axis J3 but is disposed in the image display apparatus 1 so that theaxis J3 is present in the plane F, an increase in the size of theapparatus resulting from the thickness in the direction of the axis J3is minimized.

Further, the drawing laser light LL having passed through the prism 3 isincident on the light reflection portion 414 in a direction inclined tothe axis J3. An angle θ between the axis J3 and the drawing laser lightLL incident on the light reflection portion 414 is not limited to aspecific value but is preferably greater than or equal to about 30° butsmaller than or equal to about 60°.

When the drawing laser light LL is incident on the light reflectionportion 414 in a direction inclined to the axis J3 (normal to lightreflection surface 414 a), the drawing laser light LL deflected by theoptical scanner 40 for scanning can exit out of the enclosure 9 withoutinterfering with other members (prism 3, for example) in the enclosure9. It is therefore not necessary to provide a flat mirror, a prism, orany other optical component for changing the optical path of the drawinglaser light LL deflected by the optical scanner 40 for scanning, wherebythe size of the image display apparatus 1 can be reduced.

Further, in the optical scanner 40, the amplitude of the oscillation(angle of swing motion) of the resonantly driven movable portion 41around the first axis J1 is greater than the amplitude of theoscillation of the non-resonantly driven movable portion 41 around thesecond axis J2. The optical scanner 40 is disposed so that the amplitudein the Z-axis direction is greater than the amplitude in the in-planedirection in the XY plane. That is, the optical scanner 40 is disposedso that the first axis J1 (shafts 421 and 422) is parallel to thein-plane direction in the XY plane (coincides with the plane F) and thesecond axis J2 (shafts 441, 442, 443, and 422) is parallel to the Zaxis. Disposing the optical scanner 40 as described above provides thefollowing advantageous effects.

Since the drawing laser light LL is incident on the light reflectionportion 414 in a direction inclined to the axis J3 as described above, adrawable region S shaped as shown in FIGS. 8A and 8B is irradiated withthe drawing laser light LL deflected by the light reflection portion 414for two-dimensional scanning. FIG. 8A shows a drawable region availablewhen the optical scanner 40 is disposed so that the first axis J1 isparallel to the in-plane direction in the XY plane and the second axisJ2 is parallel to the Z axis as described in the present embodiment.Conversely, FIG. 8B shows a drawable region available when the opticalscanner 40 is disposed so that the first axis J1 is parallel to the Zaxis and the second axis J2 is parallel to the in-plane direction in theXY plane. As shown in FIGS. 8A and 8B, the distortion of the drawableregion S in FIG. 8A is smaller than in FIG. 8B, whereby the drawableregion S in FIG. 8A provides a larger effective rectangular drawingregion (region actually irradiated with drawing laser light LL for imagedisplay) S′ ensured in the drawable region S than in FIG. 8B. Therefore,the drawable region S can be used more effectively in FIG. 8A than inFIG. 8B, and a more efficient, larger image can be drawn.

The optical scanner 40 is preferably disposed so that the drawableregion shown in FIG. 8A is provided but may alternatively be disposed sothat the drawable region shown in FIG. 8B is provided.

1-4. Detector

The detector 5 has a function of detecting the intensity of the drawinglaser light LL (each of the laser light RR, GG, and BB). The thusconfigured detector 5 includes a light receiving device 51, such as aphotodiode, disposed in the enclosure 9. The light incident surface 31of the prism 3 is configured to slightly (at a reflectance of about0.1%, for example) reflect the laser light RR, GG, and BB, and the lightreceiving device 51 is located on the optical paths of the reflectedlight. The light receiving device 51 outputs a signal (voltage) having amagnitude according to the intensity of each of the received reflectedlight, and the intensity of each of the laser light RR, GG, and BB canbe detected based on the signal.

Information on the detected intensities of the laser light RR, GG, andBB is sent to the controller 6, which then controls the drive operationof the laser light sources 21R, 21G, and 21B based on the receivedinformation.

Specifically, the reflectance and transmittance representing how muchthe collimator lenses 22R, 22G, and 22B and the dichroic mirrors 23R,23G, and 23B reflect and transmit the laser light RR, GG, and BB and thereflectance representing how much the light incident surface 31 reflectsthe laser light RR, GG, and BB are measured in advance, and themeasurement information is stored in a memory (not shown) in thecontroller 6.

Subsequently, for example, before image drawing is initiated, thecontroller 6 sends a drive signal of a predetermined magnitude (voltage)to the drive circuit associated with the laser light source 21R, whichthen emits the laser light RR. Part of the laser light RR is thenreflected off the light incident surface 31 of the prism 3, and thelight receiving device 51 receives the reflected light and detects theintensity thereof. The actual intensity of the laser light RR emittedfrom laser light source 21R is then determined based on the reflectancestored in the memory described above and representing how much each ofthe portions described above reflects the laser light RR. Therelationship between the intensity of the laser light RR and themagnitude (voltage value) of the drive signal is thus determined, andthe magnitude of the drive signal necessary to provide the laser lightRR of a predetermined intensity is found.

The relationship is stored in the memory described above. To draw animage, the controller 6 sends the drive circuit a desired drive signal,based on the relationship, that causes the laser light source 21R toemit a laser light RR of a desired intensity. The same holds true forthe laser light GG and BB. Specifically, the relationship between theintensity of each of the laser light GG and BB and the magnitude of thecorresponding drive signal is determined, and the controller 6 sends,based on the determined relationships, the drive circuit desired drivesignals that cause the laser light sources 21G and 21B to emit laserlight GG and BB of desired intensities.

Drawing laser light LL of a desired color and luminance can thus beproduced, and the image display characteristics are improved.

The above description has been made with reference to the case where therelationship between the intensity of the laser light RR and themagnitude (voltage value) of the drive signal is provided before imagedrawing is initiated. The relationship is not necessarily providedbefore image drawing is initiated and may, for example, be provided inthe course of image drawing. The effective drawing region S′ in thedrawable region S is irradiated with the drawing laser light LL, whereasthe other region (non-drawing region S″) is not irradiated therewith, asdescribed above. In view of the fact described above, the relationshipbetween the intensity of the laser light RR and the magnitude (voltagevalue) of the drive signal may alternatively be provided as describedabove during a period when an image is being drawn but the movableportion 41 (light reflection portion 414) faces the non-drawing regionS″ and no drawing laser light LL is outputted.

1-5. Controller

The controller 6 has a function of controlling the operation of thedrawing light source unit 2 and the light scan section 4. Specifically,the controller 6 drives the optical scanner 40 to cause the movableportion 41 to swing around the first and second axes J1, J2 and drivesthe drawing light source unit 2 to output the drawing laser light LL insynchronization with the swing motion of the movable portion 41. Thecontroller 6 drives the laser light sources 21R, 21G, and 21B to emitlaser light RR, GG, and BB of predetermined intensities at predeterminedtimings based, for example, on image data sent from an external computerso that the drawing laser light LL of a predetermined color andintensity (luminance) is outputted at a predetermined timing. As aresult, an image according to the image data is displayed on the object10.

The configuration of the image display apparatus 1 has been described indetail.

In the image display apparatus 1 described above, the members thereof,that is, the laser light sources 21R, 21G, and 21B, the collimatorlenses 22R, 22G, and 22B, the dichroic mirrors 23R, 23G, and 23B, theprism 3, the optical scanner 40, and the light receiving device 51 arearranged in a flat plane (the same plane) extending in the direction inwhich the XY plane extends. The optical axes of the laser light RR, GG,and BB emitted from the laser light sources 21R, 21G, and 21B and theoptical axis of the drawing laser light LL, which is the combination ofthe laser light RR, GG, and BB, are present in the same plane (firstplane F) parallel to the XY plane until the laser light RR, GG, and BBor the drawing laser light LL is incident on the optical scanner 40.Further, the light reflection surface 414 a is disposed so that it isperpendicular to the plane F. Moreover, in the image display apparatus1, since the prism 3 inclines the optical axis of the drawing laserlight LL within the plane F, the components of the image displayapparatus 1 (optical scanner 40, in particular) can be arranged in theflat plane. In this case, the components of the image display apparatus1 can be aligned with one another in the flat plane, whereby the imagedisplay apparatus 1 can be readily assembled. Further, in the imagedisplay apparatus 1, since the prism 3 shapes the drawing laser lightLL, excellent image display characteristics are provided. Moreover, thenumber of parts can be reduced, and the size of the apparatus can bereduced accordingly.

2. Heads-Up Display

A description will next be made of the configuration of a heads-updisplay based on the image display apparatus according to the embodimentof the invention.

FIG. 9 is a perspective view showing a heads-up display based on theimage display apparatus according to the embodiment of the invention.

In a heads-up display system 200, the image display apparatus 1 isaccommodated in a dashboard of an automobile to form a heads-up display210, as shown in FIG. 9. The heads-up display 210 can display apredetermined image, such as a displayed image that guides a driver to adestination, on a windshield 220. The heads-up display system 200 is notnecessarily used with an automobile and may be used, for example, withan airplane and a ship.

3. Head-Mounted Display

A description will next be made of a head-mounted display based on theimage display apparatus according to the embodiment of the invention(head-mounted display according to the embodiment of the invention).

FIG. 10 is a perspective view showing a head-mounted display accordingto the embodiment of the invention.

A head-mounted display 300 includes glasses 310 and the image displayapparatus 1 mounted on the glasses 310, as shown in FIG. 10. The imagedisplay apparatus 1 displays a predetermined image in a display section(light reflection member) 320 provided in a portion of the glasses 310that originally functions as a lens, and the image is viewed with one ofthe eyes.

The display section 320 may be transparent or opaque. When the displaysection 320 is transparent, information from the image display apparatus1 can be superimposed on information from the real world and thesuperimposed information can be viewed. Further, the display section 320only needs to reflect at least part of light incident thereon and can,for example, be a half-silvered mirror.

The head-mounted display 300 may alternatively be provided with twoimage display apparatuses 1, and two display sections may display imagesviewed with both eyes.

The image display apparatus and the head-mounted display according tothe embodiments of the invention have been described with reference tothe drawings, but the invention is not limited thereto. Theconfiguration of each of the components can be replaced with anarbitrary configuration having the same function. Further, otherarbitrary components may be added to the embodiments of the invention.

Further, the above embodiment has been described with reference to thecase where the frame of the optical scanner, specifically a lowerportion of the frame in FIG. 5, is formed to be thicker than the base ofthe movable portion and the permanent magnet is fixed to the lowersurface of the thus formed frame, but the configuration of the frame isnot limited thereto. For example, the frame may be formed so that it hasthe same thickness as that of the base. In this case, to prevent thebase from coming into contact with the permanent magnet fixed to thelower surface of the frame, a recess (clearance) may be formed in theupper surface of the permanent magnet.

The entire disclosure of Japanese Patent Application No. 2012-127449filed Jun. 4, 2012 is incorporated by reference herein.

What is claimed is:
 1. An image display apparatus comprising: aplurality of light source sections each of which outputs a light; alight combining section that combines the light from the plurality oflight source sections; and an optical scan section that deflects thecombined light from the light combining section for two-dimensionalscanning around a first axis and a second axis perpendicular to thefirst axis, wherein an optical axis of the light outputted from each ofthe plurality of light source sections and directed through the lightcombining section toward the optical scan section is present in a firstplane, the optical scan section includes: a base that swings around thefirst axis and the second axis, a light reflection plate having a lightreflection surface that reflects the light from the light combiningsection, the light reflection surface having an area larger than an areaof the base, and a spacer that connects the base and the lightreflection plate to each other, the first axis is present in the firstplane, the second axis is parallel to a normal of the first plane, andthe light reflection surface is perpendicular to the first plane whenthe optical scan section is not driven.
 2. The image display apparatusaccording to claim 1, wherein the light reflection surface is irradiatedwith the combined light traveling in a direction inclined to a normal tothe light reflection surface.
 3. The image display apparatus accordingto claim 1, wherein an amplitude of the swing motion of the base aroundthe first axis is greater than an amplitude of the swing motion of thebase around the second axis.
 4. The image display apparatus according toclaim 1, wherein the optical scan section includes: a frame thatsurrounds the base, a support that supports the frame, a first shaftthat connects the base to the frame so that the base is rotatable aroundthe first axis relative to the frame, and a second shaft that connectsthe frame to the support so that the frame is rotatable around thesecond axis relative to the support.
 5. The image display apparatusaccording to claim 4, wherein the light reflection plate is spaced apartfrom the first shaft in a thickness direction of the light reflectionplate but overlaps at least a part of the first shaft when viewed in athickness direction.
 6. The image display apparatus according to claim4, wherein the first shaft is disposed in parallel to an in-planedirection in the first plane, and the base resonantly swings around thefirst axis by resonantly driving a first oscillation system includingthe light reflection plate, the spacer, the base, and the first shaft.7. The image display apparatus according to claim 5, wherein a width ofthe frame in a direction of the normal to the first plane is smallerthan a width of the frame in an in-plane direction in the first plane.8. The image display apparatus according to claim 5, wherein the opticalscan section further includes a permanent magnet provided on the frameand a coil that faces the frame and produces a magnetic field that actson the permanent magnet.
 9. The image display apparatus according toclaim 1, further comprising: a prism on an optical axis of the combinedlight from the light combining section, the prism inclining the opticalaxis of the combined light from the light combining section, andchanging a cross-sectional shape of the combined light.
 10. The imagedisplay apparatus according to claim 9, wherein the light from each ofthe light source sections is linearly polarized light that behaves ass-polarized light with respect to a light incident surface of the prism.11. The image display apparatus according to claim 9, wherein the prismincreases a width of the cross-sectional shape of the combined light inan in-plane direction in the first plane.
 12. The image displayapparatus according to claim 9, wherein a light exiting surface of theprism is a light collecting lens surface.
 13. The image displayapparatus according to claim 1, wherein a radiation angle of the lightoutputted from each of the plurality of light source sections in thedirection of the normal to the first plane is greater than a radiationangle of the outputted light in an in-plane direction in the firstplane.
 14. The image display apparatus according to claim 2, wherein anamplitude of the swing motion of the base around the first axis isgreater than an amplitude of the swing motion of the base around thesecond axis.
 15. The image display apparatus according to claim 5,wherein the first shaft is disposed in parallel to an in-plane directionin the first plane, and the base resonantly swings around the first axisby resonantly driving a first oscillation system including the lightreflection plate, the spacer, the base, and the first shaft.
 16. Theimage display apparatus according to claim 6, wherein a width of theframe in the direction of the normal to the first plane is smaller thana width of the frame in the in-plane direction in the first plane. 17.The image display apparatus according to claim 10, wherein the prismincreases a width of the cross-sectional shape of the combined light inan in-plane direction in the first plane.
 18. The image displayapparatus according to claim 10, wherein a light exiting surface of theprism is a light collecting lens surface.
 19. The image displayapparatus according to claim 11, wherein a light exiting surface of theprism is a light collecting lens surface.
 20. A head-mounted displaycomprising: a light reflection member that reflects at least part oflight incident thereon; and an image display apparatus that irradiateslight to the light reflection member, the image display apparatusincluding: a plurality of light source sections each of which outputs alight, a light combining section that combines the light from theplurality of light source sections, and an optical scan section thatdeflects the combined light from the light combining section fortwo-dimensional scanning around a first axis and a second axisperpendicular to the first axis, wherein an optical axis of the lightoutputted from each of the plurality of light source sections anddirected through the light combining section toward the optical scansection is present in a first plane, the optical scan section includes:a base that swings around the first axis and the second axis, a lightreflection plate having a light reflection surface that reflects thelight from the light combining section, the light reflection surfacehaving an area larger than an area of the base, and a spacer thatconnects the base and the light reflection plate to each other, thefirst axis is present in the first plane, the second axis is parallel toa normal of the first plane, and the light reflection surface isperpendicular to the first plane when the optical scan section is notdriven.
 21. The image display apparatus according to claim 1, whereinthe plurality of light source sections are provided along apredetermined direction, and light emitting directions of the pluralityof light source sections are the same.
 22. The image display apparatusaccording to claim 21, further comprising: a prism provided on anoptical axis of the light combined by the light combining section,wherein the prism inclines the optical axis of the light combined by thelight combining section, the prism is placed on a first extension of theoptical axis of the light emitted from one of the plurality of lightsource sections, and the optical scan section is placed on a secondextensions of the optical axis of the light emitted from the other ofthe plurality of light source sections.